Extension-ladder.



l G. W. .MoHR'sTAD EXTENSION LADDER. I APPLICATION FILED JUNE 14, 1909.

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Patented Apr.11 ,1911.

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G. W. MOHRSTADT. EXTENSION LADDER. APPLIUATION FILED JUNE 14. 1909.

`989,389 Patented Apr. 11, 1911.

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WITNESSES ATTOR Ex/,

tirar@ EXTENSION-LADDER.

Specification of Letters Patent.

Application led June 14, 1909.

Patented Apr. 11, 1911.

Serial No. 502,098.

To all whom it 'may concer/n:

Be it known that I, GUs'rAv W. Morin-I s'rADr, of the city of Toronto,in the Province of Ontario, Canada, have invented certain new and usefulImprovements in Extension- Ladders, of which the following is aspecication.

This invention relates to ladders which are adapted to be carried incompact form or extended to any desired length within their limits. Suchladders have usually been formed either in separate connectible sectionsor in sections slidable upon one another.

1 attain the desired result by formino the ladder in sections hingedtogether and adapted to be wound on a drum, means being provided forautomatically locking the sections in alinement as they are unwound fromthe drum. Means are also provided for rotating the drum in eitherdirection and for varying the inclination of the ladder asmay bedesired.

Figure 1 is a side elevation of aladder constructed in accordance withmy invention. Fig. 2 is a front elevation of the same. Fig. 3 is a sideelevation of the opposite side of the apparatus. Fig. 4 is a detailillustrating the automatic lock between the ladder sec- 30 tions. Fig. 5is a perspective detail illustrating the automatic locking andinterlocking of the sections. Fig. 6 is a front elevation partly insection. Fig. 7 is a side sectional elevation of the mechanism foraltering the angle of the ladder. Fig. 8 is a plan view of the guideroller of the ladder. Fig. 9 is a sectional detail of the brake. Fig. 10is a detail of the clutch connection employed between two of the pinionsof the operating gear. In the drawings like letters of referenceindicate corresponding parts in the different figures.

1 is a frame in which is j ournaled a drum 2. The frame 1 will usuallybe mounted upon a suitable vehicle whereby it may be transported fromplace to place, but as such vehicle forms no part of the presentinvention it is not illustrated.

The drum is preferably polygonal composed of side plates connected bycross bars 3. The ladder is formed of a plurality of sections 4 hingedtogether at 5. The sides of the ladder sections are preferably angle 55bars, as shown. Portions of the lower part of each angle bar of eachsection are cut away at the joints so that they overlap, as shown inFigs. 4 and 5, the tongue which is at the lower end of each angle bar ofeach section resting in contact'with the lower side of the adjacentangle bar of the next section. The sections are thus prevented fromhinging one on the other except in the direction necessary to wind themon the drum.

The method of joining the sections also brings the lower part of thesides of each section in alinement with the corresponding parts in theother section. A rack 7 may thus be formed on or connected to thesections in such a manner that when the sections of the ladder are inalinement the rack is in effect continuous throughout the length of theladder.

The rst section of the ladder is pivotally connected with the drum bymeans of the cross bar 8. As the sections of the ladder cverlie oneanother, as shown, they neces sarily increase regularly in length fromthe inner end to the outermost or top section.

The sections of the ladder are held in 4alinement by suitable lockswhich operate automatically as soon as a section has been brought intoalinement with an adjacent section. l show for this purpose at each sideof the ladder at each joint a pin 9 connected to a spring 10. These pinsare adapted to enter holes formed in the sides of the sections wherethey overlap (see particularly Figs. 4 and 5). The sections of theladder as they are unwound from the drum pass between the guide rollers11 and 12. The latter is preferably formed as a gear pinion engaging theracks 7 on the ladder sections. The purpose of this arrangement willhereinafter appear. The roller 11 is j ournaled on a slide 13 movable inthe guide 14 carried on a part of the frame 15 which will be hereinafterdescribed. This slide 13 has a spindle 16 connected therewith passingthrough a cross bar of the guide 14. A nut 17 is threaded on thisspindle and serves to adjust the tension of a coil spring 18 located onthe spindle between the nut 17 and the cross bar of the guide 14. Theladder is thus firmly but yieldingly pressed into en* gagement with thegear roller 12. The result of this arrangement of the guide rollers withthe drum is that when the -sections are drawn from the drum and as thedrum is rotated the sections are consecutively straightened intoalinement and are automatically locked by the means already described.It is also desirable that when the ladder is being re-wound on the drumthat t-he sections should be automatically unlocked as soon as a jointhas passed below the guide rollers 11 and 12. For this purpose I providenear the corners of the polygonal drum the knife edge projections 19 andI also sharpen to a knife edge each tongue G. The result of this is thatas the sections are wound on to the drum the projections 19 and thetongues 6 engage beneath the ends of the springs 10 and withdraw thepins 9 sufliciently to unlock the joints and allow the sect-ions to bendon one another as they are wound on the drum. It is evident also that aseach section is unwound the springs 10 of its joints are successivelydisengaged from the tongue 6 or the projections 19, as the case may be,and the spring left free to automatically lock the joints as thesections are brought into alinement again.

It follows that the method of unlocking the sections which I employ,that the stepwise reduction of the sections in width combined with theprogressive increase in length is of the greatest importance and indeedis essential to success.

The sections being all parallel to the opposite sides of the drum, thejoints of those sections Wound directly on the drum are kept closer tothe sides of the drum than if the sections tapered in width which isimportant as these sections are unlocked by the projec tions 19.Furthermore, the step-wise reduction in width permits the lower ends ofcertain sections to be projected as the tongues 6 to engage and unlockthe joints of overlapping sections which is a very simple, cheap andeffective arrangement.

To rotate the drum and to extend the sections I provide the followingmechanism: A shaft 2O is j ournaled on one side of the frame and carriesa gear pinion 21. This shaft may be rotated by hand, but in large sizesof the apparatus will probably require to be motor driven. This pinion21 meshes with a gear wheel 22 loose on the spindle 23 of the drum. Thisgear wheel 22 meshes with a train of gearing 24 journaled on the frame15 and meshing with the gear pinion 25 loose on the spindle 2G of thegear roller 12. This pinion is adapted to be put into driving connectionwith the gear roller preferably by being provided with a recess 27adapted to engage the projection 28 at the end of the gear roller 12. Anordina-ry clutch shifter 29 is provided to place the pinion 25 into andout of clutch with the roller. From this arrangement it follows that byrotating the shaft 20 the gear roller 12 may be rotated to draw theladder sections from the drum as required.

As the weight of the ladder will assist the rewinding process I amenabled to utilize quicker acting gearing to rewind the ladder.

F or this purpose I secure to the drum the gear wheel 30. Meshing withthis gear wheel is a pinion 31 which is connected by means of anordinary free wheel clutch 32 with a pinion 33 on the same spindle. Thispinion 33 meshes with the pinion 21. Owing to the free wheel clutch thepinion 30 is inoperative when the ladder is being raised, but becomesoperative to reverse the drum when the pinion 21 is reversed and thisreverses the direction of the movement of the pinion 33.

It is necessary to alter the inclination of the ladder according to theheight to be reached and the distance of the apparatus from the buildingto be reached. The frame 15 is therefore made to swing on the spindle 26of the drum. The lower end of this frame is provided with a cross barand has connected thereto a link 35 pivotally connected to a cross head34 movable in the guides 36 secured to the base of the frame 1. A screw37 is connected to this cross head and has a nut 38 thereon which isheld from endwise motion by being tted in a recess in the bearing block39 through which the screw 37 passes. This nut 38 is also formedexteriorly as a worm pinion engaged by the worm 40 on the spindle 41journaled in the bearing block 39 and part of the frame 1.

A spindle 42 provided with a crank handle 43, or other means whereby itmay be rotated, is journaled in the frame 1 and is connected by a trainof gearing 44 to the spindle 41. By operating the crank handle thelink34 through the intermediate parts may be moved in either direction torock the frame 15 and thus alter the inclination of the ladder. Ofcourse power means might be employed if desired to operate the spindle42, or indeed other means might be employed for rocking the saidswinging frame.

Clamp screws 45 working through arc shaped slots in the frame 1 andscrewing into the frame 15 may be used to clamp the ladder if desired ina rigid position.

To lock the drum in any desired position I prefer to employ a ratchetwheel 46 secured to the drum at the opposite side to the gear wheels 22and' 30. This ratchet` wheel is engaged by a spring actuated pawl 47. Apin 48 connected to a spring 49 operates through a hole in the frame 1and is adapted to enter a hole 5() in the pawl to hold the ladder out ofmesh with the ratchet wheel when the drum is to be operated to rewindthe ladder.

It will have been noticed that when the clutch shifter 29 has been movedto disengage the pinion 25 from the gear roller 12 that there is nothingto support the weight of the extended part ofthe ladder. The weight ofthe extended ladder would therefore tend to strip from the frame thesection larly shaped recess in the frame.

wound thereon adjacent to the extended .por tion of the ladder. In.order to overcome this diiiiculty I provide in .connection with thegear roller 12 a brake which is brought into operation by thedisengaging movement of the clutch shifter 29. This brake veffectuallycounterbalances the weight of the ladder and enables the sections of theladder to be wound upon the drum, as hereinbefore described. Theconstruction of this brake is best seen on reference to Figs. (Sand 9.

The spindle 26 is loos-e in the gear roller 12. The gear roller is heldfrom endwise movement without interference with its rotation by theretainer 51 which is secured to the frame 15 and engages a groove in theroller. The spindle 26 is however rotated independently of the pinion 27but is so connected with the latter that the longitudinal movements ofthe pinion relative to the gear roller are imparted to the spindle. Forthis purpose 1 show a set screw 52 screwed through the hub of the pinionand engaging the groove in the spindle. The other end of the spindle hasa tapered friction clutch member 53 secured to or formed thereon adaptedto engage a similar shaped recess formed in the end of the gear roller12. Outside the clutch member 53 the spindle 26 is suitably shaped toengage the frame 15 to prevent rotation of the spindle when the latterhas been moved to engage the clutch member 53 with the recess in thegear roller. For this purpose I show a square end 54 on the end of thespindle adapted to engage a simi- From this construction it follows thatwhen the pinion 27 is thrown out of engagement with the roller 12 theclutch member 53 will simultaneously be engaged with the roller to applya brake to the movements of the latter.

The clutch shifter 29 may be held as moved by being sprung into thenotches of a notched quadrant 55 secured to the frame 15 as shown inFig. 6.

From the above description it will be seen how compactly the laddeil maybe carried and how simple is the operation of extending or retractingthe same.

In practice many of the details of construction may be varied withoutdeparting from the spirit of my invention.

l/Vhat I claim as my invention is 1. An extension ladder comprising asuitably journaled polygonal drum; a series of ladder sections hingedtogether, an end section being connected to the drum and the length ofthe -sections progressively increased and their widths decreasedstepwise according to their distance from the said end section; meansfor locking the sections in alinement; means on the drum adapted toengage and release the locks of the sections wound directly on saiddrum; and tongues on the inner sections adapted to engage and releasethe locks on the sections wound over them on the drum, said tonguesbeing formed by projecting the lower ends of the sides of the sectionspast the pivots between these sections.

2. An extension ladder comprising a suitably journaled drum; a series ofladder sections hinged together an'd adapted to be wound on the drum;means for locking the sections in alinement; a movable frame, pivotedintermediate its ends on the same axis as the drum; a guide roller onsaid frame over which the ladder sections pass; and means for adjustingsaid frame to adjust the angle of the ladder, applied to the lower endof said frame.

3. An extension ladder comprising a suitably journaled drum; a series ofladder sections'hinged together and adapted to be wound on the drum;means for locking the sections in alinement; a movable frame, pivotedintermediate its ends on the same axis as the drum; a guide roller onsaid frame over which the ladder sections pass; and means for adjustingsaid frame to adjust the angle of the ladder, comprising a screwpivotally connected to the lower end of the frame; a journaled nutthrough which the screw is threaded; and means for rotating the nut.

4. An extension ladder comprising a suitably journaled drum; a series ofladder sections hinged together with sides overlapping, and providedwhere they overlap with holes which are in alinement when the sectionsare extended; springs connected to the outer section at each joint; pinssecured to said springs adapted to enter the alined holes; and knifeedge projections on the drum, adapted to engagebeneath said springs tounlock the sections wound immediately on the drum.

5. An extension ladder comprising a suitably ournaled drum; a series ofladder sections hinged together with sides overlapping, and providedwhere they overlap with holes which are in alinement when the sec*vtions are extended; springs connected to the outer section at eachjoint; pins secured to said springs adapted to enter the alined holes;knife edge projections on the drum, adapted to engage beneath saidsprings to unlock the sections wound immediately on the drum; and knifeedge tongues formed on each section, adapted to engage the springs ofsections wound over them to una releasable clutch connection in thegearing between the shaft and one of the parts to which it is geared;and a free wheel clutch in the gearing between said shaft and the otherpart to which it is geared.

7. An extension ladder comprising a suitably journaled drum; a series ofladder sections hinged together and adapted t0 be wound on the drum;means for locking the sections in alinement; rack sections formed on theladder sections; a gear roller engaged by the rack sections; anoperating shaft geared to the roller and also to the drum; a releasableclutch connection in the gearing between the shaft and the gear roller;and a free wheel clutch in the gearing between the said shaft and thedrum.

8. An extension ladder comprising a suitably journaled drum; a series ofladder sections hinged together and adapted to be wound on the drum;means for locking the sections in alinement; rack sections formed on theladder sections; a gear roller engaged by the rack sections; anoperating shaft geared to the roller and also to the drum;

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

ya releasable clutch connection in the gearing between the shaft and thegear roller; a free wheel clutch in the gearing between the said shaftand thedrum; and abrake for controlling the roller when the releasableclutch is disengaged.v

9. An extension ladder comprising a suitably journaled drum; a series ofladder sections hinged together and adapted to be wound on the drummeans for locking the sections in alinement; rack sections formed on theladder sections; a gear roller engaged by the rack sections; anoperating shaft geared to the roller; a clutch connection between thegear roller and said gearing; a brake; means for simultaneously applyingthe brake and disengaging the clutch; and rewinding means 'directlyactuating kthe drum.

Toronto, this 8th day of June 1909.

GUSTAV W. MOHRSTADT.

Signed in the presence of- J. EDW. MAYBEE, D. S. TOVELL.

Washington, D. C.l

